There may be no single cause of bipolar disorder (aka manic depression). Instead, research indicates the causes of bipolar disorder are probably a combination of biochemical, genetic and environmental factors that may trigger and perpetuate the chemical imbalances in the brain.
Net worth: $829 million. Telecommunications mogul Strive Masiyiwa is widely regarded as the richest man in Zimbabwe and is one of the richest men in Africa with a net worth of more than US$800 million.
Aliko Dangote, the world's wealthiest black person Oprah Winfrey at the White House in 2010, the first female black billionaire and the only black billionaire from 2004 to 2006 According to Forbes 2014 ranking of the world's billionaires, Nigerian business magnate Aliko Dangote with a net worth of $25 billion is the world's richest black person.